Method of coating shaped can ends



July 14, 1936. ON EST 2,047,692

METHOD OF COATING SHAPED CAN ENDS Original Filed Aug. 6, 1934 2 Sheets-Sheet l July .14, 1936. A. KRONQUEST METHOD OF COATING SHAPED CAN ENDS 2 Sheets-Sheet 2 Original Filed Aug. 6, @934 50 a protective enamel.

Patented July 14, 1936 METHOD OF COATING SHAPED CAN ENDS Alfred L. Kronquest, Syracuse, N. Y., assignmto, Continental Can. Company, Inc., New York, N. Y., a corporation of New York Original application August c, 1934, Serial No.

Divided and this application February 8, 1935, Serial No. 5,657

1 Claim. (01. 91-68) The invention relates to new and useful im provements in a method of applying a protective enamel to a can end which has been shaped ready for attachment to a can body. Considerable difl'iculty has been experienced in the coating of a can end which is cone-shaped and terminates in a neck which may be closed by an ordinary crown seal. In my prior application Serial No. 738,749, filed August 6, 1934, there is shown and described an apparatus for coating such a shaped can end. The present application is a division of this prior application, and the invention is directed to the method of coating the can end disclosed therein.

An object of the invention is to provide a method of coating can ends wherein an air blast may be used in connection with centrifugal force for evenly distributing the coating on the inner and outer faces of the shaped can end.

In the drawings which show one form of apparatus for carrying out the method- Figure 1 is a view partly in side elevation and partly in section showing an apparatus embodying the improvements;

Fig. 2 is an enlarged view showing the can end with the coating applied thereto and positioned for rotation for distributing the coating evenly over the inner and outer surfaces of the can end;

Fig. 3 is a detail view showinga. portion of the neck of the can end with the coating trapped in the pocket formed by the bead at the mouth of the neck of the can end and prior to subjecting the same to the air blast; and

Fig. 4 is a similar view showing the thinning of the coating by the air blast as the end is rotated.

In the drawings there is shown a shaped can end which includes a body portion I, a. channel 2 which is of the usual construction for forming the double seam in the can body, and a neck 0 portion 3. The body portion I is cone-shaped, and the neck portion is provided with ahead 4 at its upper end which extends from an opening 5 through the neck portion to a'shoulder Ii. This is for the purpose of providing a shoulder under- 45 neath which the projections on the crown seal closure may engage for the sealing of the container. Applicants present invention has to do with the method of coating the inner and outer faeesof a. shaped can end such as described with The method consists in the applying of the coating to the end and then the rotating of the end and the subjecting of the end to a gentle blast of air in the regions where the coating is likely to be trapped, so that through- 55 the combined action of the centrifugal force, and

the force of the air blast, the coating will be evenly distributed over the entire inner and outer surfaces of the can end. The apparatus as illustrated consists of a supporting frame i, which is provided with a tank 8 in which is maintained a bath of coating enamel, indicated at 9, The frame is provided with an arm In which overhangs the bath. Mounted in this arm is a sleeve II which is formed with a rack i2 at one side thereof. A gear l3 meshes with thisrack. The gear I3 is carried by a shaft i4 mounted in suitable bearings in the frame and attached to the shaft is a handle I5. By rotating the shaft through the aidof the handle, the sleeve it may be raised and lowered in the supporting arm.

Extending throughthe' sleeve is a shaft "5' which is hollow. Said shaft is mounted for rotation in bushings i1, i1 carried-by the sleeve i I. Fixed to the upper end of this hollow shaft I6 is a cone friction gear [8. Said cone friction gear i8, when the sleeve II is raised, is brought into contact with the cone friction gear i9 mounted on the outer end of a shaft 20 of a motor M which is mounted on the supporting frame I. The motor rotates continuously, and when the sleeve ii is raised so as to bring the friction gear it into contact with the friction gear It, then the shaft It will be rotated, and rotated very rapidly. The motor is preferably of a type that will impart a speed of between three and four thousand revolutions per minute to the shaft l5. Fixed to the lower end of the shaft I6 is a chuck 2|. Said chuck 2| is provided with a series of spring arms 22, 22. These spring arms are bent outwardly and curved at 23 so as to conform tothe outer surface of the bead 4 at the neck of the can end. The lower ends of these spring arms are bent outwardly as indicated at 24- The can end is placed against these outwardly tapered extending ends 24 and forced into the curved portions which conform to the bead 4 and will be firmly gripped by these spring arms and thus held attached to the chuck. After the end is attached to the chuck, then the lever I5 is turned in a counterclockwise direction so as to lower the shaft and completely immerse the can end in' the bath of enamel. After the end has been completely immersed, it is lifted from the bath with a coating of enamel adhering to the inner and outer surfaces thereof. As soon as the friction gear l8 contacts with the friction gear l9, then the shaft will be rotated rapidly and this will rotate the end very rapidly. Centrifugal force acting on the coating will cause the coating to flow toward the extreme periphery of the can end. There will be left, however, a thin film of adhering coating over the entire surface of the end, both on the inner and outer faces thereof. The surplus coating will be discharged from the periphery of the end.

During the rotation of the end, the recess formed in the inner face of the bead 4 serves to trap the enamel so that the centrifugal force cannot alone move the enamel from the recess. This is due to the fact that portions of the inner surface of this beaded portion are necessarily of greater diameter than portions of the neck therebelow.

Extending down through the shaft I6 is a pipe 25. Said pipe is provided with a distributing head 26 on the lower end thereof, and said distributing head is formed with a series of openings 21. This pipe 25 is connected to a valve housing 28 which is attached to a pipe line 29 leading to a suitable source of air supply. The pipe 25 is so disposed that when the sleeve I6 is raised to bring the friction gears into contact, that the head 26 is moved down through the opening in the end so that air blasts coming from the openings 21 will contact with the enamel in the trap formed by this inner curved surface at the beaded neck. The air blast is gentle so as not to strip the enamel completely from this surface, but it will cause the enamel to flow from the recess or trap to a point where it will be taken up by centrifugal force and carried along by the flowing enamel so that it will be distributed and the surplus discharged. The blast of air may be so regulated that the coating of enamel throughout the entire inner surface of the end will be substantially of uniform thickness, and the entire metal surface completely covered by the enamel.

In order to regulate the flow of air from the nozzle, there is an arm 30 attached to the shaft I I, which arm is connected by a link 3I to an arm 32 connected to a valve in the valve casing 28. When the shaft is lowered for the purpose of applying the coating to the end, the valve is closed, and when the shaft is raised to the position shown in Figures 1 and 2, then the valve is opened so that air flows through the pipe and is discharged against the surface of the end. The blast of air will be released at the same time when the end begins its rotation, and will continue while the end is being rotated.

The arm I0 is provided'with a bracket 33 in which is mounted a brake member 34. Said brake member has a reduced shank 35 surrounding which is a spring 36. The Spring bears against the head of the brake member, and also against an abutment 31. The purpose of the spring is to hold the brakemember projecting from the bracket as indicated in Fig. 1. Said brake member is provided with a tapered face 38 at its upper side and the tapered face 39 at its lower side. This brake member is so positioned that when the shaft is lowered from the position shown in Fig. 1, sufliciently to disconnect the gear I8 from the gear I9, the gear I8 will contact with the brake member and stop its rotation. This is the proper positioning of the shaft for the attaching of the end to the chuck. While said gear I8 is resting against the brake member, the end is placed on the chuck, and then the shaft is lowered, and 'as it is lowered gear I8 forces the brake member to recede. 0n the upward movement of the shaft, the gear will again pass the brake member and be freed therefrom so that it may be rotated.

The apparatus as described in detail, is claimed in my copending application referred to above. The method, in detail, consists in the attaching of the end to the chuck, then the immersing of the end in the bath for coating the surface thereof, after which the end is withdrawn from the bath and rotated. At the same time that the end is rotated, it is subjected to a gentle blast of air for the purpose of dislodging the enamel from any trap formed by the shaping of the end, so that the centrifugal force, together with the air blast, will bring about an even distribution of the enamel throughout the entire surface of the can end, thus producing a very thin film completely covering the surface of the metal. After the end is coated, it is dried and may be baked in order to set or harden the enamel. Any desired enamel may be used which may be flowed over the surface of the end. Instead of immersing the end in order to provide an initial supply of enamel, it may be applied to the end by spraying, but preferably the end is dipped, as this produces a surplus of enamel which can be spread over the surface of the end and the surplus discharged, leaving a more uniform coating and insuring that the entire surface of the metal will be coated, particularly the inner faces thereof, so that no product within the container can contact with the metal.

Having thus described the invention, what I claim as new and desire to secure by Letters- Patent, is

The method of applying a protective enamel to a formed can end having a cone-shaped portion and a neck portion disposed centrally thereof and projecting from said cone-shaped portion consisting in dipping the can end into a bath of protective enamel, lifting the end from the bath and rotating said end for distributing the enamel adhering thereto uniformly over the surface of the end, applying a blast of air against the inner surface of the neck portion during the rotation of the end for forcing the excess enamel from the neck portion on to the cone-shaped portion whereby the excess enamel is discharged from the peripheral edge of said end.

ALFRED L. KRONQUEST. 

